WEST PALM BEACH, Florida -- Sen. Tammy Duckworth, a former U.S. Army helicopter pilot, said recently that the Marine Corps, Navy and Air Force would have to wait their turn if they want their own version of the Army's futuristic helicopters being developed under the Future Vertical Lift (FVL) effort.

Both the Valor and the Defiant prototypes are promising designs, Army officials maintain, that are capable of flying at speeds of more than 200 knots and will result in a replacement for the venerable Black Hawk as the service's new Future Long Range Assault Aircraft (FLRAA).

Duckworth, a former Army National Guard officer who lost both legs after enemy forces shot down the Black Hawk she was flying over Iraq in 2004, said she intends to keep the FVL program from morphing into an unwieldy, joint effort. That's a pitfall that has thrust many joint-service programs into program delays and cost-overruns because of overly broad requirements.

"This is an Army aircraft; we need to keep an Army mission," Duckworth told reporters at the Feb. 20 flight demo. "If the other services want to fall in behind it and develop something afterward and tweak it for what they need, that is fine, but we cannot build a Frankenaircraft ... that's going to meet the Marines' needs and the Navy's need and the Air Force's needs.

"We need to not let the requirements start to meander and creep around because otherwise we will never get to where we need to and get these things fielded as quickly as possible," she added.

In the past, the Pentagon has often tried to develop multiple versions of a major combat system, such as the new F-35 Joint Strike Fighter, which has been designed to satisfy the requirements of the Navy, Marine Corps and Air Force. The acquisition program for the advanced, stealth fighter began in the mid-1990s and still suffers from testing setbacks that have delayed a full-rate production decision.

That Army-Marine Corps Joint Light Tactical Vehicle (JLTV) program, however, is considered a successful acquisition effort that began in 2006 after Humvees in Iraq could not withstand the destruction force of enemy homemade bombs attacks.

JLTV took almost a decade to become a reality but, in August 2015, Oshkosh Corp. was selected over Lockheed Martin Corp. and AM General LLC to build the vehicle for the Army and Marine Corps.

FVL is one of the Army's top modernization priorities under a new strategy the service launched in 2017, with the goal of replacing most of its major combat platforms beginning in 2028.

Leaders stood up Army Future Command, an organization designed to help the service's acquisition and requirements machines work more closely together in an effort to streamline what has traditionally been a slow-moving process to develop and field combat system.

So far, the strategy appears to be working, since the FLRAA and the Future Attack Reconnaissance Aircraft (FARA) efforts are ahead of schedule, Duckworth said.

Army officials are scheduled to down-select to two vendors to build final prototypes of the FARA next month. The service is also scheduled to begin a competitive demonstration and risk reduction phase for FLRAA, which is expected to last until 2022, the year the service plans to down-select to one vendor to build the Black Hawk replacement.

"This is rare for defense procurement to actually be ahead of timeline instead of pushing everything to the right," Duckworth said. "I am very pleased with how well the Army is handling this development."

The senator stressed, however, that she intends to continue strict oversight of the FVL to ensure it doesn't result in a waste of taxpayer dollars.

"We can't be spending upward of $60 million per airframe," Duckworth said. "If we do that, then we can't field the number of airframes that we need to be out there in the force."

Army Secretary Ryan McCarthy, who also attended the flight demo, stressed that the service's leadership is committed to making necessary cuts to outdated programs to free up money for FVL and other modernization efforts.

"We don't have a choice. We are running out of letters to upgrade the existing platforms -- they are 40-year-old systems; the technology will not endure," he said.